Question

问题，我有，是我迷路了。我不知道从哪里开始这项任务。

这就是文本文件的样子

文件名是“districtpopulation”

ALABAMA,Abbeville,2955

ALABAMA,Adamsville,4771

ALABAMA,Addison,720

ALABAMA,Alabaster,28904

ALABAMA,Alexander_City,15053

ALABAMA,Aliceville,2457

ALABAMA,Andalusia,8727

ALABAMA,Anniston,23736

ALABAMA,Arab,7694

ALABAMA,Ardmore,1145

ALABAMA,Ariton,747

ALABAMA,Ashford,1967

ALABAMA,Ashland,1856

ALABAMA,Ashville,2503

ALABAMA,Atmore,7452

ALABAMA,Auburn,53160

ALABAMA,Autaugaville,885

ALABAMA,Bay_Minette,7674

ALABAMA,Bayou_La_Batre,2761

ALABAMA,Bear_Creek,1016

ALABAMA,Berry,1212

ALABAMA,Bessemer,28217

您必须实施的命令是：

•平均所有

o将所有地区的平均人口打印到控制台

•平均值

o将给定状态列表的平均人口打印到控制台

•top x all

o将所有地区人口最多的前x区打印到控制台，x是用户输入的任何正整数

•top x

o打印州内每个州的人口最多的前x个百分比列表到控制台，x是用户输入的任何正整数

•退出

o退出程序

任何接受a的命令都必须对列表中的每个状态执行所需的操作。例如命令：

top 2 michigan new_york

应具有以下输出（数据已组成）

MICHIGAN:

            Detroit: 123453

            Flint: 4323532

        NEW_YORK:

            New_York_City: 2342342

            Some_other_city: 2342342

这是我和同学一起组织的

import java.io.File;
import java.util.Scanner;


public class Database {

    public static String[] data = new String[9000];
    public static int count;

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        boolean keepGoing = true;

        //other setup as needed


        while (keepGoing) {
            String command = keyboard.nextLine();
            String[] commandParts = command.split(" ");

            //if (commandParts[0].equalsIgnoreCase("average"))
                //if (commandParts.length == 2)   //do other stuff check for other things


             // else if ( . .. .) {


            //else if user entered in "exit"
            //keepgoing = fals      }

        //MiChIgAN == MICHIGAN 
        }
    }


    public static void readDataFile(String fileName) throws Exception {
        File dataFile = new File(fileName);
        Scanner fileReader = new Scanner(dataFile);

        while (fileReader.hasNextLine()) {
            data[count] = fileReader.nextLine();
            count++;
        }

        fileReader.close();

    }

    public static void topXAll(int x) {
        //print out the top x
    }

    //..top state
    // gettopforstate ..


    public static void averageAll() {
        System.out.println("my results here");
    }

    public static void averageList(String[] input) {
        String output = "";

        //for each state in state list {
            //output += getAverageForState(stateName);

        System.out.println(output);
    }

    public static String getAverageForState(String stateName) {
        return "";
    }

    //this is how we do stuff
    public static void doStuff() {
        String[] parts;

        for (int i = 0; i < count; i++) {
            parts = data[i].split(",");
            String stateName = data[0];
            String districtName = data[1];
            int population = Integer.parseInt(data[2]);


        }
    }

}

Answer 1

您需要创建File对象并检查while(keyboard.hasNext() or hasNextLine())，而不是检查while(keepgoing)。您应该将File对象作为Scanner的参数传递。当您想要从控制台读取时，会传递System.in。

File file = new File("file.txt");
Scanner fileInput = new Scanner(file);

while (fileInput.hasNextLine()){
    String command = inputFile.nextLine();
    // do something
}

另外，我在您的代码//MiChIgAN == MICHIGAN中将其视为评论。确保您不会陷入尝试将字符串与==进行比较的臭名昭着的陷阱。使用equals()

编辑： 此外，您可能希望使用逗号而不是空格进行拆分。文本

之间没有空格分隔符

String command = keyboard.nextLine();
String[] commandParts = command.split(",");

将文本文件应用于代码

1 个答案: